10 years ago, if you said “let’s play,” you were probably talking to three friends, at most.

But in 2015, when someone like PewDiePie says “let’s play,” he’s inviting over 36 million people to hang out and play video games. That’s like the entire population of Canada getting together to watch you play Flappy Bird.

Videos in which a person plays a game while adding commentary, often called “Let’s Play” videos, have become a global, cultural phenomenon. But the keyword here isn’t “play,” it’s “let’s.” That’s because even before you start the video, you’re being invited into a group to join in the fun. Every day, every hour, all the time, millions of people accept that invitation, driving billions of hours of let’s play videos watched across YouTube.

But what’s perhaps even more impressive: this trend has allowed some talented creators to become celebrities just by being themselves -- and playing video games. You might have already heard of PewDiePie - a Swedish gamer who receives 76 million views to his channel a week and is gaining subscribers at a rate of approximately 3.6 new subs a minute.

But let’s consider another let’s play pioneer: Markiplier, a creator known for his love for playing survival horror games. You probably haven’t seen him on the newsstands or the latest red carpet. But with 7 million subscribers and growing, he’s one of YouTube’s most popular creators, and over the past year, his name has been searched for by YouTube users 10 times more often than Jay-Z.

There’s also Vanoss, a gamer known for his ingenuity when playing popular games like Garry’s Mod, who has over 12 million YouTube subscribers. That’s 5 million more than even the most popular talk shows featuring major “A-list” celebrities. (Maybe they should try booking Vanoss?)

Let’s Play videos provide casual forums for just hanging out and sharing a passion for gameplay. That’s why being a fan of a gamer on YouTube is, for many, more satisfying than following a traditional TV or movie star. You’re not just watching a video--you’re getting to know someone while they engage with something you both genuinely love.